[yen]

As I know 1% w/w= 10000 mg/L

I have seen a statement as below:
" use 25 mg/L of 33% H2SO4 solution:

Is that means that 25 mg/L is part of 33000 mg/L?
Is the equation of "1% w/w= 10000 mg/L "suitable use in all chemical solution calculation?

[sjb]

Is the equation of "1% w/w= 10000 mg/L "suitable use in all chemical solution calculation?

Consider the units of your equation, and you will see that this is only suitable for solutions that weigh 1000 kg per litre.

[Borek]

Is the equation of "1% w/w= 10000 mg/L "suitable use in all chemical solution calculation?

Consider the units of your equation, and you will see that this is only suitable for solutions that weigh 1000 kg per litre.

Huh?

Not that I know how to understand the original question. Perhaps literally - take 25 mg of solution of 33% sulfuric acid per litre.

[sjb]

Sorry Borek,

I was somehow trying to get the message across that % w/w only correlates to a w/v figure via density.

As you know, for instance 1% w/w KOH in EtOH is not the same as 10g of KOH in 1 litre of ethanol...

[Borek]

OK about the density message, but 1000 kg/L won't work here, more like 1.000 kg/L

[sjb]

Ahhh, my mistake. Believe me when I say the original post had a decimal point in, I went away for a coffee and convinced myself I was wrong so took it out.

Apologies for the confusion.

And yes, I agree with your interpretation of the main question.

Take 33% sulfuric, using 25 mg of this per litre of your stock solution

[semper erectus]

in other words, they have taken or used 25 mg/L which is an aliqout out of original concentration which is  33% H2SO4.don't be confused!!!!